The key to a smooth launch is having a transition that isn't too sharp at any points imo. So as you build, you'll have to lay your ski/skis down on your ramp and kind of eyeball it, judging whether or not you think the ski would flex too much going over that point in the tranny. There's no good way of doing it.
If you look at my ramp I have posted in my pics you'll know what I mean. I didn't calculate any of those angles or anything.
The 14 foot rail will feel very short when going fast but long when going slow. It's relative in the summer when speed becomes a weird thing. Since your hill is your drop in, you will just have to change from where you drop in to vary speed. This is critical and you'll find sweet spots for different tricks.